The electrophilic addition of liquid bromine () to *trans*-2-butene is a stereospecific reaction. What is the stereochemical nature of the final major product?

Question

The electrophilic addition of liquid bromine ($Br_2/CCl_4$) to *trans*-2-butene is a stereospecific reaction. What is the stereochemical nature of the final major product?

Prashant Kotian · Accepted Answer

Correct answer: B. The halogenation of alkenes with proceeds via a cyclic bromonium ion intermediate and involves strict *anti*-addition. The *anti*-addition of halogens to a *trans* symmetrically substituted alkene yields a *meso* compound (due to an internal plane of symmetry). Conversely, *anti*-addition to a *cis* alkene yields a racemic mixture. Thus, *meso*-2,3-dibromobutane is formed.

💡 Solution & Explanation

Practice 22,000+ questions like this